Frank Booth Snr writes
Steve Rainbird wrote:

We have a Damson tree (Merryweather) in our garden which has a problem.
Some of the leaves have become very "scrunched up" like a screwed up
piece of paper and some of the fruits are turning yellow. Does
anybody have an idea of what it is and what can be done to help it.

Silver leaf disease. It's a fungus that affects the Prunus family.

Genus, not family ;-)
--
Kay